On the trolley wire that supplies a power to a car of an electric railroad or railway, contact with a pantograph current collector (a pantograph) occurs each time the car passes. Because of this, the trolley wire is gradually worn out during an operation of the electric railway car, and if a replacement is not made, a rupture or breaking finally occurs and causes an accident. A wear limit is then set for the trolley wire. By using the wear limit as an index of a change of the trolley wire, the trolley wire is changed and safety of the electric railway car is secured.
As a method of measuring the wear of the trolley wire, there are mainly two methods; one is a method that directly measures a thickness of the trolley wire, the other is a method that measures a width of a trolley wire worn portion and transforms this wear width into the thickness of the trolley wire.
As one method that directly measures the thickness of the trolley wire, there is a method that measures the thickness of the trolley wire using a ruler such as a vernier caliper. This is a method that measures the thickness of the trolley wire of a portion which an operator intends to measure, using the ruler such as the vernier caliper by hand. With this method, the thickness of the trolley wire to be measured can be surely determined. On the other hand, this measurement requires manpower and cannot be automated, thus it is difficult to measure the thickness of a long distance section.
As the other method that directly measures the thickness of the trolley wire, there is a method using an optical sensor. This is a method, in which a rotation roller is pressed against the trolley wire, and by a laser radiation device and a light receiving device which are installed so that the trolley wire is sandwiched on a roller mount, an amount of received light at a sandwiched portion of the trolley wire by the devices is measured, then the thickness of the trolley wire is transformed from the amount of the received light. With this method, it is possible to continuously measure the thickness of the trolley wire. However, because of contact with the trolley wire, a low speed operation is required. Furthermore, since a measurement structure in which the trolley wire is sandwiched between sensors is employed, usage in a place where a structure that is apt to collide with sensors such as a point, an air section and an anchor, exists, is impossible. Moreover, in such place where those existing structures exist, there is a need to move the devices apart from a measurement point so as not to collide.
As the method that measures the width of the trolley wire worn portion, there is a method that measures the trolley wire worn portion by applying sodium lamp or laser light (refer to a Patent Document 1). This is a method that uses the following relation; a lower portion of the trolley wire has a round gourd shape in cross section, and, as the trolley wire is shaved by the wear and becomes flatter, the width of the shaved portion becomes wider. Then, the thickness of the shaved portion of the trolley wire is transformed from the wear width.
As the width-measuring method of the trolley wire worn portion, positions of a light source and a line sensor of a light receiving part are precisely adjusted so that a reflected light from the trolley wire worn portion is received with regular reflection when applying the sodium lamp or laser light from the light source, and the trolley wire worn portion is changed into a whiteout state by way of imaging and capturing an intense light by the regular reflection, then the width of the trolley wire worn portion is measured from a width of the whiteout portion which receives the intense light.
This manner is a non-contact manner, thus a high speed operation is possible. However, this manner is susceptible to noises such as a clamp that pinches the trolley wire and a structure which appears on the background. Further, in a case where a wrong measurement result is obtained due to some noises, there is no way to verify the result. Then, with regard to the portion of the problem as the trolley wire wear measurement, it is verified using the method directly measuring the thickness of the trolley wire in the end. In addition, it is required that the regular reflection is received by precisely adjusting an application direction and a focus of the light source and a light-receiving direction of the light receiving device.
Patent Document 1: Japanese Patent Application Kokai Publication No. 10-194015